The CGIAR Research Program on Aquatic Agricultural Systems (AAS) aims over the next six years, to improve the lives of 15 million poor and vulnerable people who depend upon diverse livelihood strategies in aquatic agricultural systems Taking a Research in Development (RinD) approach, this program represents a break from 'business as usual' for the CGIAR. The program aims to build capacity to innovate and to foster more resilient communities and aquatic agricultural systems. In AAS we seek to use research not only as a problem solving device, but more importantly as a device to empower and support people who depend upon aquatic agricultural systems (particularly the most marginalized) in a development process that they themselves define. This brief describes the Participatory Action Research (PAR) approach we are using to implement RinD in the AAS program. It is not a guide for implementation of PAR, but rather aims to provide a succinct view of how we believe PAR will enable CRP AAS research to be embedded in the development context such that it supports outcomes and we can learn from implementation.